[Pyrolysis of the Lysimachia foenum-graecum Hance extract by online pyrolysis-gas chromatography-mass spectrometry].

In order to study the pyrolytic properties of Lysimachia foenum-graecum Hance extract, it was pyrolysed and detected by online pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS). The pyrolytic experimental conditions were designed to simulate the real combustion conditions inside a burning cigarette. The sample was heated at 30 degrees C/s from 300 to 900 degrees C (held for 5 s) under the flow of 9% oxygen in nitrogen. The pyrolytic components and volatile components were compared. The results showed that 64 pyrolytic components were detected, with 88.27% of the total peak area, including linoleic acid ethyl ester (10.33%), hexadecanoic acid, ethyl ester (9.12%), 9,12,15-octadecatrienoic acid, (Z,Z,Z) - (8.03%), 2-furan-carboxaldehyde, 5-(hydroxymethyl) - (6.02%), neophytadiene (5.12%), heptadecanoic acid, ethyl ester (4.50%), acetic acid, phenyl ester (3.51%), 5-methoxy-2, 2-di-methylindan-1-one (2.73%). The number of pyrolytic components was more than that of the volatile components, and 20 components were identified in both pyrolytic components and volatile components, including higher fatty acids and their esters, neophytadiene, 2-furancarboxaldehyde, (hydroxymethyl)-, and 2 (5H)-furanone, 3-hydroxy-4, 5-dimethyl-. The on-line pyrolysis was similar to the real cigarette combustion conditions. The method is a simple, rapid and good qualitative method for the pyrolysis.

[Simultaneous determination of 14 restricted substances in flavor and fragrant by ultra high performance liquid chromatography].

An ultra high performance liquid chromatographic method was established for the separation and determination of 14 restricted substances in flavor and fragrant samples. The sample was extracted by 10% (v/v) methanol aqueous solution containing 1% (v/v) ammonia. The 14 analytes were separated in 12 min on a Waters BEH C18 column (50 mm x 2.1 mm, 1.7 microm) using acetonitrile and 10 mmol/L ammonium acetate aqueous solution (containing 0.1% (v/v) acetic acid) as mobile phases with gradient elution at a flow rate of 0.2 mL/min and 35 degrees C, and detected by a diode array detector scanned from 200 nm to 500 nm. The regression equations revealed acceptable linearity (correlation coefficients ranged from 0.995 0 to 0.999 9) in the range of 0.10 - 50 mg/L for the 14 analytes. The limits of detection (LODs) were from 0.32 mg/kg to 2.51 mg/kg. The recoveries of the 14 analytes spiked in real samples at 5, 10 and 20 mg/L were 93.0% - 121% with the relative standard deviations (RSDs) of 0.51% - 4.50%. With the advantages of accessibility, high sensitivity and good reproducibility, this simple method can be used in the simultaneous determination of the restricted substances in flavor and fragrant samples.

[Determination of pyrethroid pesticide residues in tobacco leaves and tea using stir bar sorptive extraction-thermal desorption and gas chromatography-mass spectrometry].

A novel method for the determination of 5 pyrethroid pesticide residues in tobacco leaf and tea samples was established. The pesticide residues in the samples were extracted and concentrated with stir bar, desorbed by thermal desorption system, and then determined by gas chromatography-mass spectrometry (GC-MS). The pesticide residues in the samples were extracted with a stir bar at 1 100 r/min for 1 h. The desorption was carried out at 300 degrees C for 4 min under a helium flow of 50 mL/min while maintaining a cryofocusing temperature of 0 degrees C in the CIS-4 injector of the GC-MS system. Finally, the CIS-4 injector was raised to a temperature of 300 degrees C and then the analytes were separated by GC and detected by MS. The limits of detection of this method for the tobacco leaves ranged from 3.3 ng to 11.4 ng. The recoveries of pesticides from the tobacco leaves ranged from 94.8% to 103.4% and the relative standard deviations (RSDs) of peak areas ranged from 5.3% to 8.6% (n = 6). The limits of detection of this method for tea ranged from 4.2 ng to 10.5 ng. The recoveries of pesticides from tea ranged from 98.2% to 110.1% and the RSDs of peak areas were less than 9.6% (n = 6). Therefore, this method can satisfy the requirements for the rapid analysis of pesticide residues in the tobacco leaf and tea samples.

[Analysis of chemical components in tobacco flavors using stir bar sorptive extraction and thermal desorption coupled with gas chromatography-mass spectrometry].

A novel method for the analysis of chemical components in tobacco flavors was established using stir bar sorptive extraction (SBSE) and thermal desorption coupled with gas chromatography-mass spectrometry (GC-MS). The different parameters affecting the extraction of the analytes from the samples to the poly (dimethylsiloxane) (PDMS) coated stir bars and the conditions affected thermal desorption were investigated. The optimized extraction conditions were that the sample was extracted with a stir bar (10 mm length and 0.5 mm thickness) at 1 100 r/min for 1 h at ambient temperature. Desorption was carried out from 20 degrees C ramped to 250 degrees C at 60 degrees C/min and hold for 2 min under a helium flow of 50 mL/min in the splitless mode while maintained the cryofocusing temperature of - 100 degrees C in a CIS-4 injector of the GC-MS system. Finally, the CIS-4 injector was raised to a temperature of 280 degrees C and the analytes were separated by GC and detected by MS using full scan mode (m/z 35 - 400). Under the described conditions, about 30 components were identified from the tobacco flavors, and the major components included esters, ketones, aldehydes, etc. The average relative standard deviation (RSD) of peak areas of 30 components for 6 determinations was less than 10%. The good repeatability made SBSE a powerful tool for the routine quality control analysis of chemical components in tobacco flavors.

[Study of pyrolysates of flue-cured tobacco leaves and stems].

To further understand the effect of tobacco stems in tobacco blend, a detailed comparative study of chemical components of tobacco leaves and stems before and after combustion was carried out. Pyrolysis of tobacco leaves and stems was carried out by a CDS Pyrolyser 2000 coupled to a Finnigan 8000(TOP) Gas Chromatograph and a Voyager Mass Spectrometer (GC-MS). A modified apparatus of pyrolysis was used to emulate the behavior of combustion of cigarette. A set of pyrolysis conditions was also developed that approximated those occurring in the pyrolysis region of the burning cigarette. The conditions included heating the sample at 20 degrees C/ms from 30 degrees C to 300 degrees C, 600 degrees C and 900 degrees C in air, and their pyrolysates were analyzed by GC-MS. The results indicated that the values of routine chemical constituents in tobacco leaves and stems were obviously different. The pyrolysates belonged to numerous classes of compounds such as hydrocarbons, alcohols, phenols, aldehydes, ketones, nitriles, alkaloids etc. The kinds of pyrolysates of tobacco leaves and stems were positively related to the pyrolysis temperature levels. On the other hand, at the same temperature level, the types of the pyrolysates from the tobacco leaves were much more than those from the tobacco stems.

[Study of pyrolysates of beta-carotene in tobacco].

Relationships between tobacco compounds and smoke products are complex and often difficult to unravel. Pyrolysis experiments have frequently been used to establish such relationships. The relevance of pyrolysis experiments to the behavior of tobacco constituent in a burning cigarette was studied. A set of pyrolysis conditions has been developed to study the effect of thermal degradation of beta-carotene to the cigarette smoke quality, and the conditions was approximated to those occurring in the pyrolysis region of the burning cigarette. The pyrolysates of beta-carotene were investigated in air, 10% O2 (in N2) and N2 at three temperature levels of 300 degrees C, 600 degrees C and 900 degrees C, respectively. The pyrolysates were adsorbed by solid-phase microextraction (SPME) and then analyzed by gas chromatography/mass spectrometry (GC/ MS). Under the different conditions, the major pyrolysates from beta-carotene are hydrocarbon compounds such as toluene, p-xylene, 1, 2, 3, 4-tetrahydro-1, 1, 6-trimethyl-naphthalene and 2, 7-dimethyl-naphthalene, and some important flavors existing in cigarette smoke such as isophorone, 2, 6, 6-trimethyl-1-cyclohexene-1-carboxaldehyde, beta-ionone and 5, 6, 7, 7a-tetrahydro-4, 4, 7 a-trimethyl-2 (4H)-benzofuranone. The amount of these pyrolysates alters with the change of pyrolysis temperature levels and the concentration of oxygen.